This invention relates to the drive of loads such as those associated with machine tools, by a step motor system, and includes certain improvements over the system disclosed in my said prior co-pending application, Ser. No. 465,596.
Stepped movement of a load to an interpolated position intermediate between the steps attainable by a large angle step motor may be attained by use of a small angle step motor in combination with a large angle step motor as disclosed in my prior co-pending application. However, in my prior co-pending application, the disclosed system had certain limitations overcome by the present invention. Because the housing of one step motor is driven by the other step motor, facilities were provided in the invention disclosed in Ser. No. 465,596, for limiting the amount of movement of one of the step motors to avoid wrap-up of the leads through which the driving pulses are fed to its field windings. This complicates the drive logic for the motors. It is therefore an object of the present invention to overcome the aforesaid disadvantages and problems of my prior step motor system, by feeding drive pulses via slip rings to that step motor which has the rotating housing.